19 October 2016

How the Corvette Grand Sport became an icon

Grand Sport, a venerated name in the Corvette canon, is back in the news – because it’s returning to Chevrolet showrooms.

The 2017 model is Chevrolet’s third deployment of the Grand Sport nameplate for a road-legal production model. To understand this name’s magic, however, one must return to the car that inspired them all – the five lightweight 1963 Grand Sport racecars, now the most valuable of any Corvette.

In a roundabout way, the Grand Sport legend arose from the 1955 disaster at 24 Hours of Le Mans, where a Mercedes-Benz racecar was launched into the stands, killing its driver and 83 spectators, the most catastrophic accident in racing history. Mercedes-Benz withdrew from racing following the event, and two years later the Automobile Manufacturers Association urged Detroit’s Big Three to suspend all participation in racing, blaming the inherent dangers to drivers and spectators as well as the growing perception that racing encouraged unsafe driving.

While GM took the edict pretty seriously, Ford and Chrysler were less committed. Ford had undertaken a relationship with Carroll Shelby in 1962 to build British AC Cobras modified with Ford V-8 power, and they soon began winning on the North American road racing circuit. Ford had also initiated a full-fledged effort to win the 24-hours of Le Mans with the program that resulted in the GT40.

At Chevrolet, racing still consisted of back-door support for private teams. When the second-generation Corvette debuted for 1963, customers were offered a made-to-order racing version known as the Z06. But when a team of four Z06’s took to the track at Riverside in 1963, the lone Cobra in the field, driven by Bill Krause, embarrassed them.

Zora Arkus-Duntov, Chevy’s take-action Corvette champion, knew his cars needed a severe makeover. And so the Grand Sport program was born. He and his engineers started by developing a new chassis, and they cut weight by extensively using aluminum and creating a body of paper-thin, hand-laid fiberglass. The result was a full 1,000-pound reduction from a production Sting Ray.

Next came the engine. It was to be an all-new variation of the small block V-8, displacing 377 cubic inches and fitted with aluminum hemispherical cylinder heads. On the test bed, the engine was producing 550 hp at 6,400 rpm. Duntov’s grand plan was to homologate 125 of these lightweight Corvettes, which were now eligible for international competition in a new FIA Grand Touring class.

The first mule car was completed in November 1962 and immediately taken to Sebring for testing. While the Grand Sport’s chassis and drivetrain performed beautifully, the aerodynamics of the car left something to be desired. The nose of the car lifted under acceleration; most photos of the car in action still show the rear end hunkered down as if it had a heavy load in the trunk.

Though Chevrolet’s general manager, Bunkie Knudsen, supported the program when GM’s CEO, Frederic Donner, caught wind of it, he shut down racecar production. But five Grand Sports (and a sixth chassis) had already been built. Duntov was incredulous, but reasoned that his orders from upstairs were not to build any more cars; nothing had been said about the completed cars. Duntov turned these over to trusted racing teams.

Because the official factory program came to an abrupt end, the Grand Sports did not contain all of the performance hardware that Duntov originally envisioned — notably the 377-cid engine. Instead, they had to use 327-cube small block engines that made 360 horsepower. The cars were later retrofitted with a twin-inlet Rochester fuel injection unit, which enabled Dick Thompson to record the Grand Sport’s first racing win at an SCCA event at Watkins Glen in New York.

Still, Duntov had imagined so much more. So he took perhaps the biggest risk of his career by calling the cars back to the GM Technical Center in Warren, Mich., to prepare for the Nassau Speed Week in the Bahamas, a direct violation of GM management’s policy. Duntov elected to supply three cars to a professional team led by John Mecom, a 22-year-old heir to a Houston oil fortune. Mecom had the budget and the connections to hire the best drivers: Roger Penske, Dick Thompson, A. J. Foyt, Augie Pabst and Jim Hall.

The cars were heavily modified with flared fenders, bigger wheels and wider tires – and a 377-cubic inch aluminum-block engine. All told, they were beautifully turned out, radiant in their silvery blue metallic paint.

At Nassau, they faced off against Shelby’s Cobras as well as a competitive international field. In the longest and most important race of the week, the 252-mile Nassau Trophy, the Grand Sports finished fourth and eighth after numerous pit stops to have their hoods taped down. The highest-placing Cobra came in seventh.

Despite the modest results, Duntov was ecstatic, feeling that this car might have a future after all. But GM management slammed the door again, ordering Duntov to have no further contact with the Mecom team. Everyone expected an executive order to have the cars crushed, but none emerged.

The five surviving Grand Sports are still with us, although two were modified into roadsters. All carry a performance pedigree instilled by Zora Arkus-Duntov and all will long be considered the crown jewels of collectible Corvettes.

3 Reader Comments

  • 1
    kenneth phillips Pennsylvania October 28, 2016 at 21:08
    I was in Nassau campaigning a Ferrari 250 LM and a Simca Abarth Carrera. But I had been racing a 56 Corvette since 57. It was wonderful to see real , serious, Corvettes taking on EVERYTHING. John Mecom had come to Nassau with a fine team and shocking Corvettes. If you are no longer fimular with all those drivers Roger Penske, Dr. Dick Thompson, August Pabst , Jim Hall , AJ Foyt for me I take a moment and raise my cup to one of the greatest group ever. When you say the Gran Sport Corvettes airodynamics were poor, it is a Grand understatement. The track at Nassau was an old unused airport. Flat. But overgrown souch that you could not see any of the track except what was right in front of you. When Roger Penske ( really driving, if you never saw Roger drive you missed something special) appeared from the bushes into the pit straight with the Corvette Gran Sport in an amazing slide , hard on it so that the front of the Corvette was so high it looked like Roger was doing a "Wheely" front tires off the track all the way down the straight. It is not often a race car coming by the experienced racers in the pits will be so radical that everyone steps back. In 60 years of racing I can still see and hear that Corvette coming by. Mecom's Gran Sports were parked next to us in the hanger we all used to work on the cars. When I came in one morning the Gran Sport next to our Ferrari had a big puddle of oil under it. One of the Nassau natives hired to guard Mecom's cars had shown off how loud the Gran Sports were to the other" guards" and started the Corvette and wound it up until it blew. It is hard to describe how mad Mecom was. I think they are still looking for that guard. You mention the Chev. Engines having the dual FI ( Cheeta style) but I believe these Gran Sports had cross ram Webbers. A Gran show. Thanks for the Memories.
  • 2
    Mack King MI October 28, 2016 at 11:28
    I would like to see photos of the 377 cubic in. Al block HEMI head engine that Zora developed. There seems to be a lot of secrecy about this engine and why was it not used in production Corvettes.
  • 3
    John Zink Tulsa, OK/Lake Leelanau, MI October 28, 2016 at 11:38
    I first saw two Grand Sports, one coupe and one roadster, at a car show sponsored by the Detroit Club at the Notre Dame campus. The show was put together by my classmate, Tony DeLorenzo. I am guessing that this was about 1964. Although the story doesn't give any timelines, it seems to imply that there were no roadsters that early. Can anybody clarify the timing of when the roadsters saw the light of day?

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